Valine, leucine and isoleucine are known as branched chain amino acids (BCAA), and have long been used as the components for nutritious foods, nutritious compositions for infusions, and the like as essential amino acids. The composition comprising valine, leucine and isoleucine as active components is also widely used for nutritious supplements for sports or the like since it has physiological effects such as reduction of muscle fatigue. Furthermore, the composition comprising valine, leucine and isoleucine as active components is known as drug product for treatment of hepatic diseases and as medical food used for treatment of tardive dyskinesia.
The form for oral intake of BCAA includes a beverage, a granule, a tablet and the like. Some modification is necessary in the taste in these beverage, granule and tablet since BCAA has a peculiar bitter taste. In addition, production of a tablet comprising BCAA is difficult because BCAA is apt to adhere to a punch and die of a compression molding machine and causes a compression molding problem such as capping and sticking, so there was a need to prevent the compression molding problem.
A nutritious composition for infusions which comprises dipeptide having leucine at the C-terminal is disclosed in PATENT DOCUMENT 1, a nutritious composition for infusions which comprises dipeptide having leucine at the C-terminal, valine and isoleucine is disclosed in PATENT DOCUMENT 2, and a nutritious composition for infusions which comprises dipeptide having α-aspartyl at the N-terminal and valine, leucine or isoleucine at the C-terminal is disclosed in PATENT DOCUMENT 3. A liquid nutritious composition which comprises dipeptide having glycyl at the N-terminal and valine, leucine or isoleucine at the C-terminal is disclosed in PATENT DOCUMENT 4.
A method for producing dipeptide having leucine, isoleucine or valine at the C-terminal by using a microorganism is also disclosed in Patent Document 5.
PATENT DOCUMENT 1 JP-A-2-22232
PATENT DOCUMENT 2 JP-A-3-127737
PATENT DOCUMENT 3 JP-A-62-151156
PATENT DOCUMENT 4 JP-A-61-247354
PATENT DOCUMENT 5 WO 2004/58960 Pamphlet